The present invention relates to arrangements in a radio access network of a mobile telecommunication network. An example of such a mobile telecommunication network wherein the present invention may be implemented is a Universal Mobile Telecommunication System (UMTS) Network and the radio access network of UMTS is denoted UMTS terrestrial radio access network (UTRAN). The UTRAN is illustrated in FIG. 1 and comprises at least one Radio Network System 100 connected to the Core Network (CN) 200. The CN is connectable to other networks such as the Internet, other mobile networks e.g. GSM systems and fixed telephony networks. The RNS 100 comprises at least one Radio Network Controller 110. Furthermore, the respective RNC 110 controls a plurality of Node-Bs 120,130 that are connected to the RNC by means of the Iub interface 140. Each Node-B, also referred to as base station, covers one or more cells and is arranged to serve the User Equipment (UE) 300 within said cell. Finally, the UE 300, also referred to as mobile terminal, is connected to one or more Node-Bs over the Wideband Code Division Multiple Access (WCDMA) based radio interface 150. The UMTS network illustrated in FIG. 1 is also denoted WCDMA network.
According to the current state-of-the-art, e.g. as defined by the 3GPP standards, a certain function in the UE is controlled by a control function in the RNC. Said certain function is implemented by a process which in this description is denoted as slave-process and the control function is implemented by a process which in this description is denoted master-process. In this sense, the master-process controls the slave-process. The master- and the slave-process are components of a distributed process. The execution of such a distributed process realizes a system function. Examples of such a system function are power control and Automatic Repeat reQuest (ARQ). During execution, a master-process and a slave-process are said to be engaged in a control loop, where the master-process sends commands to the slave-process where the commands are potentially based on feedback sent from the slave-process to the master-process. This is illustrated in FIG. 2. FIG. 2 shows schematically the slave-process implemented in a UE, wherein the slave-process communicates with the master-process in an RNC. The master-process sends control commands to the slave-process and the slave-process responds with feedback, e.g. measurement reports. In addition, another example of a control-loop is when a certain function in a Node-B is also controlled from an RNC but based on feedback from the UEs connected to that Node-B.
A problem that is common to both types of control-loops is that the delay in the control-loop may cause imprecise execution of the slave- and/or master-process that in turn may result in reduced performance of the corresponding system function or other functions that directly or indirectly depend on that system function.
For certain system functions such as reliable link-layer transmission based on ARQ, mobility functionality and channel re-configurations, the Node-B has more accurate/timely information than the RNC. Thus, for such system functions the Node-B is often in a better position than the RNC to execute the corresponding master-process.
A simple but inadequate solution would be to implement the master-process in the Node-B instead of the RNC. That would however require additional solutions to handle so-called intra-RNC handovers, where a UE re-connects to a new Node-B that is connected to the same RNC as the old Node-B.
Fast channel setup is considered in the PCT application SE2004000721. However, the method in SE2004000721 only discusses a method for reducing the transition from the RRC states CELL_FACH to CELL_DCH in a WCDMA system by providing the Node-B with temporary resources to be used while waiting for the final resource assignment from the RNC. (RRC states are further described in 3G TS 25.331) however in this case, the control is not completely transferred to the Node-B. The RNC is always involved in the decision and the Node-B only assigns temporary resources to the UE while waiting for the RNC decision.